 /* px em rem 等长度单位演示 */
html{
    font-size: 62.5%;/* 16px*0.625=10px */
}
body{
    font-size: 1.2px;
}
.value_px{
    font-size: 32px;
}

.value_em{
    font-size: 2em;
}

.value_rem{
    font-size: 2rem;
}

/* 颜色值 */
.color_name{
    color: red;
}

.color_hex{
    color: #00ff00;
}
.color_fun{
    color: rgb(0,0,255);
}

/* 图片函数url */
.img_url{
    width: 262px;
    height: 70px;
    background-image: url("图片/qq_logo.png");
    font-weight: bolder;
}
/* 常见字体样式属性 */
.font_demo{
    /* font: 400; */
    color: red;
    font-family: 微软雅黑,sans-serif;
    font-size: 2em;
    font-style: italic;
    font-weight: normal;
}

/* 常见文本样式属性 */
.text_demo{
    font-size: 2em;
    border: 1px solid black;
    width: 50rem;
    height: 10rem;
    text-align: left;
    line-height: 10rem;
    text-decoration: underline;
    text-indent: 3rem;
    letter-spacing: 1rem;
    word-spacing: 2rem;

}

/* 列表样式属性 */
ul{
    font-size: 2rem;
}
.list_demo1{
    list-style: circle inside;
}

.list_demo2{
    list-style: none;
}
.list_demo3{
    list-style-image: url(图片/qq_logo.png);
    list-style-type: none;
    list-style-position: inside;
}

.list_demo4{
    list-style: none url(图片/designmoo.png) inside;
}

/* 背景样式属性 */
.bg_box{
    border: 1px solid red;
    width: 40rem;
    height: 10rem;
}
.bg_demo1{
    
    background-color: coral;
}

.bg_demo2{
    background-image: url(图片/qq_logo.png);
}

.bg_demo3{
    background-image: url(图片/qq_logo.png);
    /* background-repeat: no-repeat; */
    background-repeat: repeat-y;
}
.bg_demo4{
    background-image: url(图片/qq_logo.png);
    background-repeat: no-repeat;
    background-position: center center;
}

.bg_demo5{
    background-image: url(图片/qq_logo.png);
    background-repeat: no-repeat;
    background-position: top right;
    background-attachment: fixed;
}

.bg_demo6{
    background: #bbf3bd url(图片/qq_logo.png) repeat-x top right fixed;
}

/* 表格样式 */
.table_demo{
    font-size: 2rem;
    border: 1px solid black;
    width: 70%;
    margin: 0 auto;
    table-layout: fixed;
    caption-side: top;
    border-collapse: collapse;
      /* border-collapse: separate; */
    border-spacing: 10px;
    empty-cells: show;
}

.table_demo caption{
    font-size: 2.5rem;
}

.table_demo th, .table_demo td{
    border-top: 1px solid black;
    border-bottom: 1px solid black;
    text-align: center;
}

.table_demo thead{
    background-color: hsl(0, 94%, 37%);
    color: white;
}
.table_demo tbody tr:hover{
    background-color: yellow;
    cursor: pointer;
}

.table_demo tfoot td{
    text-align: right;
    padding-right: 2rem;
}

/* 表单样式 */
.form_demo{
    font-size: 1.4rem;
    border: 1px solids seagreen;
    background-color: #fff;
    width: 35rem;
    height: 25rem;
    text-align: center;
}

.form_demo input[type="text"], .form_demo input[type="password"] {
    border-left: 0;
    border-right: 0;
    border-top: 0;
    border-bottom: 1px solid #000;
    width: 200px;
    height: 21px;
    padding-left: 26px;
}
.form_demo #username{
    background: #fff url(图片/username.png) no-repeat top left;
   
}

.form_demo #pwd{
    background: #fff url(图片/password.png) no-repeat top left;
   
}
.form_demo [type="submit"]{
    width: 100px;
    height: 38px;
    background-color: tomato;
    border: 1px dashed #2e5bec;
    border-radius: 10px;
    color: whitesmoke;
    text-align: center;
}